Telephone call recipients may block calls from undesirable call sources, such as telemarketers, on a national or on an individual level. For example, calls from call sources nationally recognized as typically undesirable may be blocked for call recipients that are registered with the National Do Not Call Registry. The National Do Not Call Registry blocks calls from the recognized call sources to all registered call recipients. The call recipients may add call sources to the National Do Not Call Registry, which results in calls from the added call sources being blocked for all registered recipients. In addition, an individual recipient may specify call sources whose calls are blocked only for the individual recipient.